CN107433288A - It is a kind of based on advancing slip milling train Convenient stable criterion - Google Patents
It is a kind of based on advancing slip milling train Convenient stable criterion Download PDFInfo
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- CN107433288A CN107433288A CN201610353400.XA CN201610353400A CN107433288A CN 107433288 A CN107433288 A CN 107433288A CN 201610353400 A CN201610353400 A CN 201610353400A CN 107433288 A CN107433288 A CN 107433288A
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- advancing slip
- milling train
- neutral angle
- slip value
- rolling
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B38/00—Methods or devices for measuring, detecting or monitoring specially adapted for metal-rolling mills, e.g. position detection, inspection of the product
Abstract
The invention discloses a kind of based on advancing slip milling train Convenient stable criterion, this method is for being widely present strip " negative advancing slip " in actual cold rolling production, by to the plasticity of strip inside and outside cold rolling area and the modeling of elastic deformation and theory analysis, derivation establishes new forward slip model, and new model can calculate the advancing slip value of rolling zone including " negative advancing slip ".Based on the new forward slip model, establish advancing slip value and rolling zone skidding discriminant relation and advancing slip value and rolling mill vibration discriminant relation, so as to preferably judge the stability problem of milling train, it specify that the quantitative relationship between advancing slip value and milling train unstability, the change that rolling technological parameter simultaneously numerous in cold continuous rolling process can directly observe advancing slip value judges milling train running status to predict, implements the on-line monitoring to milling train running status.
Description
Technical field
The present invention relates to the technical field of steel rolling process application, rolled more particularly to a kind of based on advancing slip
Machine Convenient stable criterion.
Background technology
Strip is the stem product of steel and iron industry, its production technology level and Mass accuracy alignment target
The state-of-art of a national steel and iron industry.Cold-rolled steel sheet with its excellent processability,
It is widely used in each main department of the national economy such as automobile, household electrical appliances, light industry, building, turns into one
The important industrial raw materials of kind.
With the change of the market demand, the yield of Thin Specs (thickness≤0.5mm) strip steps up.
Thin gauge strip flakiness ratio is big, and reduction ratio is big, and speed of production is high.In the operation of rolling, rolled piece goes out
Mouth speed is referred to as advancing slip phenomenon slightly larger than the phenomenon of roll speed.Advancing slip is the weight in the operation of rolling
Technological parameter is wanted, is equally also played an important role in operation of rolling control.In recent years, with cold
Tandem rolling comes into operation to high speed, very thinization development and laser velocimeter, in the last machine of cold continuous rolling
There is " negative advancing slip " this phenomenon in frame or rear two frames measured result indicating strip, i.e. rolled piece goes out
Mouth speed is less than the peripheral speed of roll.Strip " negative advancing slip " is widely present in being produced for actual cold rolling,
And various advancing slip computation models can not all provide negative advancing slip value at present, strip easily occurs when " negative advancing slip "
Skidding influences easily to cause rolling mill vibration when surface quality and too big advancing slip value.It is outstanding in actual production process
Milling train skidding easily occurs on its fast state or unstable phenomenon occurs in vibration, influences normally to produce, causes
Product quality is unqualified, and easily causing production accident under serious conditions jeopardizes personal safety.
Therefore, in order to ensure that thin gauge strip leads to plate in the stabilization of tandem mills, unit need to be combined and given birth to
Production feature, propose a kind of method for improving mill milling process stability.
The content of the invention
The present invention is in order to overcome the above-mentioned deficiencies of the prior art, there is provided a kind of steady based on advancing slip milling train
Qualitative discrimination method.
The technical solution adopted in the present invention is：
It is a kind of based on advancing slip milling train Convenient stable criterion, comprise the following steps：
S1, using Bland-Ford roll-force formula, obtain public for the advancing slip Dresden of cold continuous rolling
Formula：R ' is working roll radius in formula；For neutral angle size；hout
To export belt steel thickness；foutFor advancing slip value.
S2, Dresden formula are modified.
Assuming that there is one to continue rolling outlet strip with working roll symmetrical " spill roller ", when " spill
When roller " is identical with strip speed, now the cornerite of " spill roller " and strip is defined as new neutral angle
And thinkThe advancing slip value that can be calculated after the neutral angle of hypothesis now is found, derivation is with before
Face is consistent, can obtain revised Dresden formula：
R ' is working roll radius in formula；For neutral angle size；houtTo export belt steel thickness；foutFor
Advancing slip value；
S3, to forward slip model centering angleIt is modified：
Revised advancing slip calculation formula is as follows：
R ' is working roll radius in formula；For neutral angle size；For revised neutral angle；houtFor
Export belt steel thickness；fout' it is the revised advancing slip value of neutral angle；For neutral angle correction size；
Δ l is contact arc length variable quantity.
S4, milling train stability distinguishing standard are：Work as foutDuring ' ＜ 1, milling train is unstable, occurs advancing slip.
Warning output and provide under S5, unusual service condition and solve countermeasure to avoid advancing slip phenomenon from occurring.
As the improvement of above-mentioned technical proposal, in the actual operation of rolling, due to depositing for rolling differential gap
Causing skidding also can not necessarily occur when being less than 1 even if the advancing slip value that actual measurement obtains, only
When advancing slip value it is small to a certain extent when can just skid, therefore consider the presence of operation of rolling differential gap,
Calculate critical advancing slip value of skidding.
R ' is working roll radius in formula；For neutral angle size；For critical skidding neutral angle；L is contact
Arc length；fout" for critical advancing slip value of skidding；
Milling train stability distinguishing standard is：Work as fout" during ＜ 1, milling train is unstable, skids.
As the improvement of above-mentioned technical proposal, roller system is calculated by stability criterion and vibrates facing for unstability
Boundary's speed, then by forward slip model calculate corresponding to it is critical advancing slip, you can be used as rolling mill vibration
Criterion.
R ' is working roll radius in formula；It is critical mill speed vrcWhen corresponding neutral angle；houtFor outlet
Belt steel thickness；Critical mill speed vrcWhen corresponding advancing slip value；
Milling train stability distinguishing standard is：WhenWhen, milling train is unstable, vibrates.
Beneficial effects of the present invention：It is a kind of based on advancing slip milling train Convenient stable criterion, by cold
The plasticity of strip and the modeling of elastic deformation and theory analysis inside and outside rolling zone are rolled, derivation establishes new
Forward slip model, the model can calculate the advancing slip value of rolling zone including " negative advancing slip ".It is new based on this
Forward slip model, establish advancing slip value and sentence with rolling zone skidding discriminant relation and advancing slip value with rolling mill vibration
Other relational expression, so as to preferably judge the stability problem of milling train.
Brief description of the drawings
Fig. 1 is working roll and rolled piece rolled structure figure；
Neutral angle when Fig. 2 is negative advancing slip assumes definition；
Fig. 3 is stagnant zone (differential gap) schematic diagram；
Fig. 4 is changing rule of the vibration critical speed with coefficient of friction；
Fig. 5 is changing rule of the advancing slip value of vibration critical with coefficient of friction；
Fig. 6 is changing rule of the vibration critical speed with resistance of deformation；
Fig. 7 is changing rule of the advancing slip value of vibration critical with resistance of deformation.
Fig. 8 is main flow chart.
Embodiment
In order that the technical means, the inventive features, the objects and the advantages of the present invention are readily apparent from
Understand, with reference to being specifically illustrating, the present invention is expanded on further.
When it is implemented, with reference to Fig. 8 main flow charts, it is a kind of based on advancing slip milling train stability distinguishing side
Method, comprise the following steps：
S1, with reference to Fig. 1 working rolls and rolled piece rolled structure figure, using Bland-Ford roll-force formula,
The advancing slip Dresden formula for cold continuous rolling are obtained, calculate the advancing slip value of rolled piece：
Wherein R ' is working roll radius；For neutral angle size；hout
To export belt steel thickness；foutFor advancing slip value.
S2, calculate the advancing slip value f for finding to be calculated with Dresden formulaout1 is all higher than, this and reality
Situation is not inconsistent.So Dresden formula are modified.
Neutral angle when bearing advancing slip with reference to Fig. 2 assumes definition, it is assumed that have one it is symmetrically " recessed with working roll
Shape roller " continues rolling outlet strip, when " spill roller " is identical with strip speed, now " spill
The cornerite of roller " and strip is defined as new neutral angleAnd think
Revised Dresden formula can be calculated after finding the neutral angle of hypothesis.
Wherein R ' is working roll radius；For neutral angle size；houtTo export belt steel thickness；foutFor
It is advancing slip.
S3, nip angle increase being understood according to forward slip model, the advancing slip value being calculated with master mould is less than normal,
So need further to be modified forward slip model neutral angle：
For neutral angle correction size；Δ l is contact arc length variable quantity；For revised neutral angle；
Revised advancing slip calculation formula is as follows：
R ' is working roll radius in formula；For revised neutral angle；houtTo export belt steel thickness；
fout' it is the revised advancing slip value of neutral angle.
S4, milling train stability distinguishing standard are：Work as foutDuring ' ＜ 1, milling train is unstable, occurs advancing slip.
S4.1, the critical advancing slip value of operation of rolling skidding calculate.
In the actual operation of rolling, due to rolling the presence of differential gap, even if before causing actual measurement to obtain
When being less than 1 skidding also can not necessarily occur for sliding value, only when advancing slip value it is small to a certain extent when
It can skid, therefore consider the presence of operation of rolling differential gap, with reference to Fig. 3 stagnant zones (differential gap)
Schematic diagram, calculate critical advancing slip value of skidding.
L is contact arc length in formula,For critical skidding neutral angle, recycle
Advancing slip calculation formula obtains critical advancing slip value of skidding,
R ' is working roll radius in formula；For neutral angle size；For critical skidding neutral angle；fout" to beat
Sliding critical advancing slip value；
Milling train stability distinguishing standard is：Work as fout" during ＜ 1, milling train is unstable, skids.
S4.2, roll and rolled piece skin-friction coefficient and deformation of rolled wire influenceed according to the change of mill speed
The change of drag, unstability critical speed and critical advancing slip influence are analyzed.It is accurate by stability
Then calculate roller system vibration unstability critical speed, then by forward slip model calculate corresponding to it is critical before
It is sliding.
R ' is working roll radius in formula；It is critical mill speed vrcWhen corresponding neutral angle；houtFor outlet
Belt steel thickness；Critical mill speed vrcWhen corresponding advancing slip value；
Milling train stability distinguishing standard is：WhenWhen, milling train is unstable, vibrates.
Under S5, unusual service condition warning output and provide solve countermeasure with avoid skid, oscillation phenomenon occur.
The present invention is applied to certain tandem mills of factory 1420, improves the steady of the cold continuous rolling operation of rolling
It is qualitative.With reference to Fig. 4 vibration criticals speed with coefficient of friction changing rule, Fig. 5 vibration criticals are advancing slip
Value is with changing rule, figure of the changing rule, Fig. 6 vibration criticals speed of coefficient of friction with resistance of deformation
For value that 7 vibration criticals are advancing slip with the changing rule of resistance of deformation, design parameter value is as follows：
Certain factory cold continuous rolling F4 frames hin4=0.62mm, hout4=0.50mm and F5 frames
hin4=0.50mm, hout4=0.42mm is typical rolling schedule, takes the friction coefficient μ ∈ [0.02,0.19] to be
Affecting parameters, calculate unstability critical speed under different coefficients of friction of F4 frames and F5 frames and preceding
Sliding value.Under the typical rolling schedule, when coefficient of friction is 0.03, F4 frame mill speeds exceed
1250m/min, advancing slip value, which are more than 1.053, to be vibrated；F5 frame mill speeds exceed
1680m/min, advancing slip value, which are more than 1.032, to be vibrated.Using F4 frames as object, set
The technological parameter such as identical rolling pressure and tension force, changes deformation of rolled wire drag, calculates the critical speed of unstability
Degree and critical advancing slip value.Under the typical rolling schedule, when deformation of rolled wire drag is 840MPa, F4
Frame mill speed is more than 1.0533 more than 1340m/min, advancing slip value to be vibrated.
Under the typical rolling schedule, the critical advancing slip value of F4 frames skidding is 0.964, i.e., advancing slip value is small
May occur skidding when 0.964, F5 frames critical advancing slip value of skidding is 0.943, i.e., before
When being less than 0.943 skidding may occur for sliding value.
It is more than 85% to rolling mill vibration forecast accuracy after applying the present invention to the production line, it is right
Milling train skidding forecast accuracy is more than 82%, effectively increases the stability of mill milling process, carries
High product quality.
General principle, principal character and the advantages of the present invention of the present invention has been shown and described above.This
The technical staff of industry it should be appreciated that the present invention is not limited to the above embodiments, above-described embodiment and
Merely illustrating the principles of the invention described in specification, before spirit and scope of the invention is not departed from
Put that various changes and modifications of the present invention are possible, these changes and improvements both fall within claimed sheet
In invention scope.The claimed scope of the invention is defined by appended claims and its equivalent.
Claims (5)
- It is 1. a kind of based on advancing slip milling train Convenient stable criterion, it is characterised in that including with Lower step：S1, using Bland-Ford roll-force formula, before obtaining the Dresden for cold continuous rolling Sliding calculation formula；S2, calculating advancing slip to Dresden are modified,Assuming that there is one to continue rolling outlet strip with working roll symmetrical " spill roller ", when " recessed When shape roller " is identical with strip speed, now the cornerite of " spill roller " and strip is defined as new Neutral angleAnd thinkThe advancing slip calculation formula of revised Dresden are obtained,R ' is working roll radius in formula；For neutral angle size；houtTo export belt steel thickness；fout For advancing slip value；S3, centering angleIt is modified, obtains revised neutral angleThe revised advancing slip Dresden calculation formula of neutral angle are as follows,R ' is working roll radius in formula；For revised neutral angle；houtIt is thick for outlet strip Degree；fout' it is the revised advancing slip value of neutral angle；S4, milling train stability distinguishing standard are：Work as foutDuring ' ＜ 1, milling train is unstable, before generation It is sliding；Warning output and provide under S5, unusual service condition and solve countermeasure to avoid advancing slip phenomenon from occurring.
- 2. according to a kind of based on advancing slip milling train Convenient stable criterion described in claim 1, Characterized in that, advancing slip calculation formula is in the step S1 R ' is working roll radius in formula；For neutral angle size；houtTo export belt steel thickness；foutFor Advancing slip value.
- 3. according to a kind of based on advancing slip milling train Convenient stable criterion described in claim 1, Characterized in that, the step S3 neutral angles are modified to, R ' is working roll radius in formula；For neutral angle correction size；Δ l is Contact arc length variable quantity；For neutral angle size；For revised neutral angle.
- 4. according to a kind of based on advancing slip milling train Convenient stable criterion described in claim 1, Characterized in that, in the S4 milling trains stability distinguishing standard, when advancing slip value is less than 1 also not Be bound to occur skidding, only when advancing slip value it is small to a certain extent when can just skid, Consider the presence of operation of rolling differential gap, calculate critical advancing slip value of skidding；R ' is working roll radius in formula；For neutral angle size；For critical skidding neutral angle；l For contact arc length；houtTo export belt steel thickness；fout" for critical advancing slip value of skidding；Milling train stability distinguishing standard is：Work as fout" during ＜ 1, milling train is unstable, skids.
- 5. according to a kind of based on advancing slip milling train Convenient stable criterion described in claim 1, Characterized in that, in the S4 milling trains stability distinguishing standard, calculated by stability criterion Go out roller system vibration unstability critical speed, then by forward slip model calculate corresponding to it is critical advancing slip Value,R ' is working roll radius in formula；It is critical mill speed vrcWhen corresponding neutral angle；houtFor Export belt steel thickness；Critical mill speed vrcWhen corresponding advancing slip value；Milling train stability distinguishing standard is：WhenWhen, milling train is unstable, vibrates.
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108296284A (en) * | 2018-01-18 | 2018-07-20 | 太原科技大学 | A kind of computational methods of the snakelike Calculating Rolling Force Energy Parameters of the synchronized reducing of steel plate |
| CN108655179A (en) * | 2018-05-31 | 2018-10-16 | 太原晋西春雷铜业有限公司 | Metal plates and strips roll advancing slip control method |
| CN109092902A (en) * | 2018-06-20 | 2018-12-28 | 新疆八钢铁股份有限公司 | The first rolling mill is prevented to sting the milling method of steel skidding |
| CN109433831A (en) * | 2018-12-14 | 2019-03-08 | 武汉利杨科技有限公司 | A kind of speeds match system reducing operation roll of mill abrasion |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2001137918A (en) * | 1999-11-16 | 2001-05-22 | Kobe Steel Ltd | Setup method of hot-rolling mill |
| CN101332474A (en) * | 2007-06-25 | 2008-12-31 | 宝钢新日铁汽车板有限公司 | Control method of rolling mill capable of preventing slipping |
| CN102553934A (en) * | 2010-12-15 | 2012-07-11 | 鞍钢股份有限公司 | Control method for forward slipping coefficient of hot rolled silicon steel |
| CN103028609A (en) * | 2011-09-30 | 2013-04-10 | 鞍钢股份有限公司 | Finishing mill forward slip coefficient control method for eliminating the intervening speed influence in manual operation |
| CN104001733A (en) * | 2014-03-11 | 2014-08-27 | 广西柳州银海铝业股份有限公司 | Control method for preventing tension measuring roller from slipping relative to continuous rolling strip |
| CN105425585A (en) * | 2015-11-11 | 2016-03-23 | 北京首钢股份有限公司 | Single-frame cold rolling force model and front sliding model debugging method |
-
2016
- 2016-05-25 CN CN201610353400.XA patent/CN107433288B/en active Active
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2001137918A (en) * | 1999-11-16 | 2001-05-22 | Kobe Steel Ltd | Setup method of hot-rolling mill |
| CN101332474A (en) * | 2007-06-25 | 2008-12-31 | 宝钢新日铁汽车板有限公司 | Control method of rolling mill capable of preventing slipping |
| CN102553934A (en) * | 2010-12-15 | 2012-07-11 | 鞍钢股份有限公司 | Control method for forward slipping coefficient of hot rolled silicon steel |
| CN103028609A (en) * | 2011-09-30 | 2013-04-10 | 鞍钢股份有限公司 | Finishing mill forward slip coefficient control method for eliminating the intervening speed influence in manual operation |
| CN104001733A (en) * | 2014-03-11 | 2014-08-27 | 广西柳州银海铝业股份有限公司 | Control method for preventing tension measuring roller from slipping relative to continuous rolling strip |
| CN105425585A (en) * | 2015-11-11 | 2016-03-23 | 北京首钢股份有限公司 | Single-frame cold rolling force model and front sliding model debugging method |
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108296284A (en) * | 2018-01-18 | 2018-07-20 | 太原科技大学 | A kind of computational methods of the snakelike Calculating Rolling Force Energy Parameters of the synchronized reducing of steel plate |
| CN108296284B (en) * | 2018-01-18 | 2019-06-11 | 太原科技大学 | A kind of calculation method of the snakelike Calculating Rolling Force Energy Parameters of the synchronized reducing of thick steel plate |
| CN108655179A (en) * | 2018-05-31 | 2018-10-16 | 太原晋西春雷铜业有限公司 | Metal plates and strips roll advancing slip control method |
| CN108655179B (en) * | 2018-05-31 | 2019-08-23 | 太原晋西春雷铜业有限公司 | Metal plates and strips roll advancing slip control method |
| CN109092902A (en) * | 2018-06-20 | 2018-12-28 | 新疆八钢铁股份有限公司 | The first rolling mill is prevented to sting the milling method of steel skidding |
| CN109092902B (en) * | 2018-06-20 | 2019-09-27 | 新疆八一钢铁股份有限公司 | The first rolling mill is prevented to sting the milling method of steel skidding |
| CN109433831A (en) * | 2018-12-14 | 2019-03-08 | 武汉利杨科技有限公司 | A kind of speeds match system reducing operation roll of mill abrasion |
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